I think I'm looking for video editing software that has some sort of 2D drawing/animation support.
For example try to imagine a video capture of a busy road from the sky and wanting to tell your viewers: "Pay attention to this specific car".
I'm looking for something that allows me to have the entire video on-screen, activate a drawing function, pause the video on a specific frame, draw a pretty box around an object, fast forward a few frames and draw the box somewhere else and have the program generate the intermediate frames (tweening).
Thanks for the suggestions. I've started evaluating Adobe After Effects CS5 but there's one problem: even if the product fulfills my requirements I feel the price is a bit too steep (retail is $999). I'm not expecting to use the product very often and it's all for personal/non-commercial use.
So... I'll probably take a look at one of the open source (and gratis) suggestions after experimenting with After Effects.